Many things can cause an animal's heart to speed up. One common thing is fright. If an animal feels threatened, it may respond with a rush of adrenaline, a stimulant that causes many heightened responses, including a faster beating heart. This could easily be what our fish is experiencing. Here is what your TAB answer should look like:
The fish's respiratory rate may have temporarily rose at the beginning of our experiment because it was frightened. Frightening an animal commonly causes it to increase its respiratory rate. It is easy to imaging a fish getting frightened when the fish was placed in a beaker, ice was added to the beaker, and a spoon began stirring its contents. While the temperature did go down slightly, the fright response to this situation could have been overpowering the effects of the slightly cooler temperature.
The fish's respiratory rate may have temporarily rose at the beginning of our experiment because it was frightened. Frightening an animal commonly causes it to increase its respiratory rate. It is easy to imaging a fish getting frightened when the fish was placed in a beaker, ice was added to the beaker, and a spoon began stirring its contents. While the temperature did go down slightly, the fright response to this situation could have been overpowering the effects of the slightly cooler temperature.